Purified 3,4-epoxycyclohexyl methyl(meth)acrylate, a process for the preparation thereof and a 3,4-epoxycyclohexyl methyl(meth)acrylate composition

ABSTRACT

Disclosed are the improvements of a process for the preparation of a purified 3,4-epoxycyclohexyl methyl(meth)acrylate and 3,4-epoxyeyclohexyl methyl(meth)acrylate which is prepared by the improvements, including only minor amounts of polymers having a low molecular weight composed of 3,4-epoxycyclohexyl methyl(meth)acrylate itself. 
     Furthermore, disclosed is a 3,4-epoxycyclohexyl methyl(meth)acrylate composition which has an excellent resistance to coloring, including a specified organic phosphorous compound.

This application is a continuation-in-part of U.S. Ser. No. 07/866,134,filed on Apr. 9, 1992, now abandoned.

FIELD OF THE INVENTION

The present invention relates to a purified 3,4-epoxycyclohexylmethyl(meth)acrylate, a process for the preparation thereof, and a3,4-epoxycyclohexyl methyl(meth)acrylate composition.

In particular, the present invention relates to the improvements of aprocess for the preparation of a purified 3,4-epoxycyclohexylmethyl(meth)acrylate.

BACKGROUND OF THE INVENTION

Heretofore, there has been widely known various acrylate monomers suchas methylacrylate, ethylacrylate, 2-ethylhexyl acrylate, etc., which aremonofunctional monomers, and trimethylolpropane triacrylate,pentaerythritol triacrylate, etc., which are multifunctional monomers.

However, the monofunctional monomers have a disadvantage that an odor ofthe residual monomer after curing causes a remarkable problem in thecase of using as a component of printing inks or coatings.

Furthermore, the multifunctional monomers also have a disadvantage thatit is necessary to be used in large amounts to resins in the case ofusing as a diluent of printing inks or coatings, resulting in loss ofexcellent properties of the resins.

On the other hand, cyclohexyl methyl(meth)acrylate itself is readilypolymerized or copolymerized with other compounds having unsaturatedgroups by heat, ultraviolet rays and or ionized radiations at thepresence of an initiator for the radical polymerization.

In particular, an epoxidized cyclohexyl methyl(meth)acrylate which analicyclic epoxy group capable of being cured by a cation, that is,3,4-epoxycyclohexyl methyl(meth)acrylate is useful for polymerizing orcopolymerizing.

3,4-epoxycyclohexyl methyl(meth)acrylate is low in viscosity and mild inodor, and has the solubility to resins over a wide range, and further itis useful for inks, coatings, adhesives, covering agents and a rawmaterial for molding resins or a modifier thereof.

It is noted that there have been basically known 3,4-epoxycyclohexylmethyl(meth)acrylate and a process for the preparation thereof,specifically by the esterification reaction of tetrahydrobenzyl alcoholwith (meth)acrylic acid or by the transesterification reaction oftetrahydrobenzyl alcohol with a (meth)acrylate ester and successively bythe epoxidation reaction with a peracid [Batog, A. E.; Zaitsev, S. Yu.;Kiryushima, N. P.; Zaitseva, V. V. (Inst. Fiz.-Org. Khim. Uglechim.,Donetsk, USSR). Zh. Org. Khim, 1982, 18(1), 90-4 (Russ)].

The reaction schemes are represented by the following formulae; ##STR1##

However, a process for the preparation of a purified, that is, acommercially available 3,4-epoxycyclohexyl methyl(meth)acrylate, has notbeen disclosed up to date.

In particular, there has not been known such a process that even a wastewater treatment is taken into consideration or even a small amount ofimpurity detected by a heptane test described hereinafter can beremoved.

On the other hand, it has been known that 3,4-epoxycyclohexylmethyl(meth)acrylate has a disadvantage of exceedingly readilypolymerizing, particularly, through the preparation processes, whilebeing stored and or shipped under the influence of heat, lights or othercauses.

In order to solve the disadvantage, Japanese Patent UnexaminedPublication (Kokai) No. 262,574/1990 teaches a method for preventingpolymerization, which uses quinones, etc. together with phosphorouscompounds under the presence of molecular state oxygen gas.

However, it has been found by the present inventors that the effect bythe method described hereinabove in which the polymerization inhibitorsare used is not sufficient in the case of preparation processes on acommercial basis.

It is one of reasons why the effect by the method was not sufficientthat there was not able to anticipate sufficient qualities to bepossessed in a product of 3,4-epoxycyclohexyl methyl(meth)acrylate,which was not produced on a commercial basis in those days when thePublication was filed.

Specifically describing, it requires that low boiling components in acommercially available 3,4-epoxycyclohexyl methyl(meth)acrylate must beremoved to the extent of from 2 to 3%, more preferably, not more than1%.

For that purpose, it requires that heating temperatures are raised andor that processing time of period is extended in the step of removingthe low-boiling ingredients.

However, raising up of the temperatures or extension of processing timeof period generates, even though minor amounts, the polymers in aproduct.

It has been found that the polymers in a product cause problems eventhough such minor amounts through the advanced developments in relationto a commercially available 3,4-epoxycyclohexyl methyl(meth)acrylate.

For example, it is one of the problems that the polymers ooze out asadhesive and insoluble substances in the case of preparing intermediatematerials of resins for coatings using 3,4-epoxycyclohexylmethyl(meth)acrylate including the polymers, resulting in causingvarious problems through processing and in producing coatings having aremarkably spoiled commercial valuation.

It appears that the minor amounts of polymers in a commerciallyavailable 3,4-epoxycyclohexyl methyl(meth)acrylate are composed of thepolymers of 3,4-epoxycyclohexyl methyl(meth)acrylate itself having a lowmolecular weight.

The contents of such polymers having a low molecular weight can be shownby weight % with a measuring method using n-heptane or n-hexane, inwhich 10 g of a product is dissolved in 100 cc of n-heptane or n-hexaneand resulting suspensions are filtered and weighed (hereinafter,occasionally referred to as HT or HT value in a solubility test).

It is known that a commercially available 3,4-epoxycyclohexylmethyl(meth)acrylate must exhibit the HT value of not more than 0.1% byweight,

It was found that the method described in Japanese Patent UnexaminedPublication (Kokai) No. 282894/1990 only can provide 3,4-epoxycyclohexylmethyl(meth)acrylate having the polymer contents of more than 0.1% byweight in HT value, more specifically, 0.14% by weight or so, whichvalues are not sufficient in quality, by a recollected confirmation testusing HT carried out thereafter.

That is, further more effective methods for inhibiting polymerizing ineach step of the preparation processes must be developed in order toproduce a purified 3,4-epoxycyclohexyl methyl(meth)acrylate on acommercial basis.

It is noted that 3,4-epoxycyclohexyl methyl(meth)acrylate has analicyclic epoxy group which tends to exceedingly readily react with anorganic acid derived from an organic peracid which is an epoxidationagent, for example, the epoxy group reacts with acetic acid derived fromperacetic acid in the case of using peracetic acid as an organicperacid, resulting in polymerization of 3,4-epoxycyclohexylmethyl(meth)acrylate and opening of the epoxy group, particularlythrough an evaporation step.

Accordingly, it is required that the organic acid is removed from acrude reaction solution as early as possible in order to maintain ashort time of period contacting with the epoxy group.

Such more effective methods do not have been developed up to date.

Furthermore, it is noted that, heretofore, various processes forremoving the organic acid and organic peracid:

(a) a refining process by distillation;

In the case of a heat resistible product, this process has been usuallycarried out.

(b) a refining process by extraction with water;

The organic acid or organic peracid, which are dissolved in a crudereaction solution, is primarily removed by an extraction with water andsuccessively by distillation, in order to prevent the polymerization orthe side reaction of an epoxy compound on distilling the crude reactionsolution without any refining processes.

(c) a refining process by neutralization;

have been applied.

In the case of incapability of removing the organic acid or organicperacid or in the case that the organic acid in an aqueous solutionreadily reacts with an epoxy compound, this neutralization process hasbeen usually applied.

Furthermore, in the case of incapability of removing the substances inwhich the polymerization and the side reaction are caused, by merelyadjusting to neutralization point of PH of the solution, the substancesare occasionally removed with an aqueous alkali solution.

Distillation is carried out in order to refine after removing thesubstances by neutralization.

However, the prior art (a) is often incapable of being applied, becauseit has a disadvantage that there are caused the polymerization or theopening reaction of epoxy groups by distillation alone because ofeasiness in the reaction of epoxy groups with an organic acid.

Furthermore, the prior arts (b) and (c), which are often applied in thecase of incapability of applying the prior art (a), are also oftenincapable of being applied in the case of the rapid reaction velocity ofepoxy groups with an organic acid.

Still further, the prior art (c) is often incapable of putting intopractice on an industrial basis because of not only large amounts of aproduct loss but also a considerable load in water treatments.

As mentioned above, the prior arts (a), (b) and (c) include difficultdisadvantages, respectively, in the case of applying on an industrialbasis.

That is, the prior arts (a), (b) and (c) have been industriallyincapable of being applied to an epoxy compound having properties that acrude reaction solution can not be refined by distillation alone becauseof the polymerization, the side reaction and that an epoxy group tendsto rapidly react with an organic acid and or water.

A first aspect of the present invention relates to a method for reducinga contacting time of period between an organic solution layer and anaqueous solution layer on extracting an organic acid and an organicperacid with water from a crude reaction solution after the epoxidationreaction.

The first aspect has been found based on the mechanism in which the lossof an epoxidized product is caused by the reaction of the epoxidizedproduct dissolved into water solution with water and an organic acid anda resultant concentration reduction of the epoxidized product andfurther repeatedly resultant dissolving, that is, by the form of areaction-extraction which accelerates further dissolving into water.

A centrifugal extractor is essentially used and retention time of periodtherethrough is essentially adjusted within 5 minutes in the firstaspect, whereby the reaction of an epoxy compound with an organic acidand water is not caused so much.

A second aspect of the present invention relates to a method for furtherremoving small amounts of them by extracting an organic acid and organicperacid with water, and more specifically the method comprisesneutralization with an alkali after separating with the apparatus asmentioned above.

It is noted that even though the centrifugal extractor as mentionedabove is used in order to remove almost of the organic acid and organicperacid by extracting with water, there can not be removed small amountsof them.

And, there is a disadvantage in a product of 3,4-epoxycyclohexylmethyl(meth)acrylate refined by distillation in order to remove solventsand other low boiling components such as small amounts of startingmaterials after removing the organic peracid by extracting alone withwater.

However, the neutralization before extracting the organic acid andorganic peracid with water can not be applied on an industrial basis,from the view point of waste water treatments, which is describedhereinabove.

The disadvantage in a product of 3,4-epoxycyclohexylmethyl(meth)acrylate is low in purity, for example, more specificallyless than 90% in purity, and such unpurified 3,4-epoxycyclohexylmethyl(meth)acrylate undesirably has the tendency of readilypolymerizing.

It is noted that there is required that the purity of the commerciallyavailable 3,4-epoxycyclohexyl methyl(meth)acrylate is from 94 to 97% byweight, and the residual components are primarily a starting material, astarting solvent and water.

From the above-described viewpoints, and as a result of studies by thepresent inventors, it has been found that a purified 3,4-epoxycyclohexylmethyl(meth)acrylate can be prepared by the various improved steps on acommercial basis.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a purified3,4-epoxycyclohexyl methyl(meth)acrylate and the improved processes forthe preparation thereof.

A first aspect of the present invention is an improved process for thepreparation of a purified 3,4-epoxycyclohexyl methyl(meth)acrylate,characterized in that a centrifugal extractor is used and retention timetherethrough is adjusted within 5 minutes in extracting with water toremove the organic peracid and an organic acid derived from the organicperacid used in the epoxidation reaction.

A second aspect of the present invention is an improved process for thepreparation of a purified 3,4-epoxycyclohexyl methyl(meth)acrylate,characterized in that an organic acid and organic peracid remained afterextracting with water are neutralized with an aqueous alkali solution,and then separated.

A third aspect of the present invention is an improved process for thepreparation of a purified 3,4-epoxycyclohexyl methyl(meth)acrylate,characterized in that 3,4-epoxycyclohexyl methyl(meth)acrylate includinglow-boiling ingredients is evaporated by different two stagesevaporation conditions.

A fourth aspect of the present invention is a process for thepreparation of a purified 3,4-epoxycyclohexyl methyl(meth)acrylate,characterized in that a crude reaction solution having3,4-epoxycyclohexyl methyl(meth)acrylate is processed by the step:

(a) extracting said organic peracid and an organic acid in the crudereaction solution derived from said organic peracid with water using acentrifugal extractor in which retention time therethrough is adjustedwithin 5 minutes in extracting with water to remove the organic peracidand an organic acid derived from the organic peracid,

(b) said organic solution layer being neutralized with an aqueous alkalisolution to form an organic solution layer and an aqueous solutionlayer, said organic solution layer being separated from said aqueoussolution layer, and successively

(c) said organic solution layer being evaporated at temperatures notmore than 100° C. and at reduced pressures to obtain a3,4-epoxycyclohexenyl methyl(meth)acrylate solution includinglow-boiling ingredients of from 3 to 50% by weight, and further

(d) said 3,4-epoxycyclohexenyl methyl(meth)acrylate solution beingevaporated at temperatures not more than 100° C. and at less than 1/2 ofthe reduced pressures in the above-mentioned (c) to obtain a purified3,4-epoxycyclohexenyl methyl(meth)acrylate including the low-boilingingredients of not more than 1% by weight.

A fifth aspect of the present invention is a 3,4-epoxycyclohexylmethyl(meth)acrylate composition including an organic phosphorouscompound represented by general formulae (I) and/or (II) describedhereinafter; ##STR2##

A sixth aspect of the present invention is a 3,4-epoxycyclohexylmethyl(meth)acrylate having a heptane test value of not more than 0.1%.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is described hereinafter in more detail.

According to a first aspect of the present invention, there is providedan improved process for the preparation of 3,4-epoxycyclohexylmethyl(meth)acrylate by the epoxidation reaction of cyclohexenylmethyl(meth)acrylate with an organic peracid, characterized in that acentrifugal extractor is used and retention time therethrough isadjusted within 5 minutes in extracting with water to remove the organicperacid and an organic acid derived from the organic peracid used in theepoxidation reaction.

The crude reaction solution to be used in the first aspect is preparedby the epoxidation reaction of cyclohexenyl methyl(meth)acrylate whichis a main starting material, with an organic peracid.

The organic peracid includes performic acid, peracetic acid,perpropionic acid, m-chloroperbenzoic acid, trifuluoroperacetic acid andperbenzoic acid.

Of these organic peracid, peracetic acid is the preferred organicperacid, because it is available on an industrial basis at a moderateprice and has a high stability.

Although the molar ratio of the organic peracid to cyclohexenylmethyl(meth)acrylate, more specifically to the double bond, istheoretically 1/1, the preferred range is from 0.1/1 to 10/1, morepreferably from 0.8/1 to 1.5/1.

If the ratio is more than 10/1, although it is preferred from the viewpoints of the conversion of cyclohexenyl methyl(meth)acrylate to3,4-epoxycyclohexyl methyl(meth)acrylate, a reduction of the time ofperiod for epoxidizing and a reduction of product losses because ofpolymerization, resulting in disadvantages of a side reaction by theexcess of the organic peracid or a reduction of selectivity of theorganic peracid, and a considerable increase of the recovery cost of theperacid.

On the other hand, if the ratio is not more than 0.1/1, although it ispreferred from the view points of a reduction of product losses, areduction of the side reaction by the organic peracid and an increase ofselectivity and further conversion of the organic peracid, resulting ina considerable increase of the recovery cost of cyclohexenylmethyl(meth)acrylate.

Accordingly, most preferably, a slightly excess amount of the organicperacid than the theoretical ratio is used because of a decomposition ofthe organic peracid, even though being small amounts, on the epoxidationreaction.

The epoxidation reaction can be preferably carried out in the presenceof a solvent. The use of the solvent for dilution is effective forlowering the viscosity of the crude reaction solution and stabilizingthe organic peracid, and further lowering the reaction velocity ofresulting epoxy group with a resulting organic acid.

The preferred solvent includes an aromatic hydrocarbon, such as benzene,toluene, xylene, ethylbenzene, iso-propylbenzene, diethylbenzene, andp-simene, an aliphatic hydrocarbon such as cyclohexane, n-hexane,heptane, hexane, octane, nonane, decane and decaline, an alcohol such ascyclohexanol, hexanol, heptanol, octanol, nonanol and furfuryl alcohol,a ketone such as acetone, methyl ethyl ketone and cyclohexanone, anester compound such as ethyl acetate, n-amylacetate, cyclohexyl acetate,isoamyl propionate, and methyl benzoate, a polyvalent alcohol such asethylene glycol, propylene glycol, ethylene glycol monomethylether,ethylene glycol monoethylether, ethylene glycol monoethylether acetate,ethylene glycol monomethylether acetate, diethylene glycolmonomethylether, diethylene glycol monoethylether an a derivativethereof, a halogenated compound such as chloroform, dimethyl chloride,carbon tetrachloride, chlorobenzene, and an ether compound such as1,2-dimethoxyetane, etc.

For example, in case that peracetic acid is used as an organic peracid,ethyl acetate is preferably used as the solvent for dilution.

Although the molar ratio of the solvent to cyclohexenylmethyl(meth)acrylate is preferably from 0.5/1 to 5/1, more preferablyfrom 1.5/1 to 3/1. If the ratio is less than 0.5/1, there becomessmaller the stabilizing effect to the organic peracid.

On the other hand, even though the ratio is more than 5/1, thestabilizing effect does not increase so much in comparison with anincrease of costs for the recovery of the solvent.

Furthermore, a polymerization inhibitor can be used together with a gasincluding molecular state oxygen in the case of carrying out theepoxidation reaction.

The preferred polymerization inhibitor includes hydroquinone,hydroquinone monomethylether, p-benzoquinone, cresol, t-butylcatecol,2,4-dimethyl-6-t-butylphenol, 2-t-butyl-4-methoxyphenol,3-t-butyl-4-methoxyphenol, 2,6-di-t-butyl-p-cresol,2,5-dihydroxy-p-quinone, piperidine, ethanolamine,alpha-nitroso-beta-naphthol, diphenylamine, phenothiazine,N-nitrosophenylhydroxylamine and N,N-diethylhydroxylamine, etc.

The use amount of the polymerization inhibitor is preferably from 0.005to 5%, more preferably from 0.001 to 0.1% by weight based oncyclohexenyl methyl(meth)acrylate which is a primary starting material.

Still further, a stabilizer for an organic peracid can be optionallyused. The preferred stabilizer includes ammonium hydrogen phosphate,potassium pyrophosphate, sodium phosphate, potassium 2-ethylhexylpyrophosphate, sodium 2-ethylhexyl pyrophosphate, tripolyphosphoricacid, potassium tripolyphosphate, sodium tripolyphosphate, sodium2-ethylhexyl pyrophosphate, potassium 2-ethylhexyl pyrophosphate,tetrapolyphosphoric acid, potassium tetrapolyphosphate, sodiumtetrapolyphosphate, 2-ethylhexyl tetrapolyphosphate, potassium2-ethylhexyl tetrapolyphosphate, sodium 2-ethylhexyl tetrapolyphosphate,potassium hexametaphosphate and sodium hexametaphosphate, etc.

There can be used one or more than one stabilizer.

The use amount of the stabilizer for the organic peracid is preferablyfrom 0.001 to 1%, more preferably from 0.01 to 0.2% by weight based oncyclohexenyl methyl(meth)acrylate which is a primary starting material,in the form of either a powder or a solution with a solvent.

The temperature region of the epoxidation reaction can be usuallyselected according to the reactivity of the organic peracid, that is,such that the epoxidation reaction advantageously occurs over thedecomposition of the organic peracid, and further such that there doesnot occur the side reaction such as the opening reaction of resultingepoxy group with an organic acid derived from the organic peracid.

In the case of peracetic acid, which is the preferred organic peracid,the preferred temperature region is specifically from 0° to 70° C.

If the temperature is lower than 0° C., there requires a long time ofperiod to complete the epoxidation reaction.

On the other hand, if the temperature is higher than 70° C., thereoccurs decomposition of peracetic acid.

The epoxidation reaction is usually carried out at ordinary pressureconditions, and also can be optionally carried out at reduced orpressurized conditions.

And, the epoxidation reaction is carried out by a continuous process ora batchwise process.

In the case of the continuous process, there can be preferably used apiston-flow type one, in the case of the batchwise process, there can bepreferably used a semi-batch type one in which the organic peracid issuccessively supplied.

More specifically, the starting material and the solvent are firstlysupplied into a reaction vessel, and then the catalyst and thestabilizer are optionally dissolved, and then the organic peracid issuccessively supplied by dropwise addition as mentioned above.

The completion of the epoxidation reaction is preferably watched by theconcentration of the residual organic peracid or gas chromatographyanalysis. After the completion of the epoxidation reaction, extractionof the organic acid and organic peracid from the crude reaction solutionwith water is carried out as described below.

The crude reaction solution generally has a composition composed of3,4-epoxycyclohexyl methyl(meth)acrylate which is a primary product,small amounts of unreacted cyclohexyl methyl(meth)acrylate which is astarting material, the residual organic peracid which is used inslightly excess amounts, the organic acid derived from the reactedorganic peracid, an optionally used polymerization inhibitor or acatalyst, and a solvent.

The crude reaction solution is supplied, as it were, as a startingmaterial in the first aspect of the present invention.

A centrifugal extractor is essentially used in the first aspect of thepresent invention.

The retention time of period while passing through the extractor whichcorresponds to a contacting time of period between an aqueous solutionand an organic solution, must be adjusted in a scope within 5 minutes,preferably within 3 minutes depending upon an approvable loss amount of3,4-epoxycyclohexyl methyl(meth)acrylate which is a primary product andthe reaction velocity between the epoxy group and the kind of theorganic acid derived from the organic peracid to be used.

The inherent minimum retention time of period depends upon a size of thecentrifugal extractor to be used.

Specifically describing, a larger sized centrifugal extractor inevitablyhas a longer inherent minimum retention time of period.

The centrifugal extractor in which two liquids are capable ofcounter-currently contacting, has a rotary body or a drum integrallymounted on a rotary shaft, the rotary body or drum having a pluralityof, specifically, 50 or so stages of ring members or perforatedcylinders, etc.

There is assembled each stage with mixing chambers and settling chambersin the rotary body or the drum of the centrifugal extractor.

A solution to be processed initially containing a solute, and a reagentfor extracting circulate counter-currently each other in the rotary bodyor drum, and mixing and separating operations performed in each stageallow the solute to pass into water.

In the mixing chamber, the two phases are mixed by the high relativespeed between the stationary part and rotating wall.

And, in the settling chamber, the two phases previously mixed areseparated by centrifugal force.

More specifically, the crude reaction solution and water which is areagent for extracting are supplied into the rotary body or drumrotating at high speed passing through two pipes connected to a rotatingshaft, respectively, and then the solution and water are contacted atthe state of a counter-current.

As the result, a heavy solution phase is radially transferred to anouterward direction of the rotary body or drum by the centrifugal force,and a light solution phase is radially transferred to an innerwarddirection of the shaft.

There can be attained the effective extraction of the organic acid andthe organic peracid from the crude reaction solution by thecounter-currents and transferences at slits between the ring members orholes on perforated cylinders. The organic acid and organic peracid canbe extracted with water within a short retention time passing throughthe extractor.

Extraction can be carried out within 5 minutes even in the case of twosolutions having a small difference between specific gravities becauseof using the centrifugal force.

Although the time of period required to extract in the centrifugalextractor also depends upon the plate efficiency, the numbers of actualplate and the kinds of liquids, that is the specific gravity differencesbetween two liquids, it is generally from several seconds toapproximately 50 minutes or so.

Accordingly, in the case of the present invention, the epoxy group doesnot react with the organic peracid, the organic acid and water so much,resulting in only minor amounts of product losses.

It is noted that the mechanism and internal structures of suchcentrifugal type counter-current apparatus are disclosed in U.S. Pat.Nos. 3,327,939, 3,814,307, 4,225,079, 4,272,011, 4,326,666 and4,367,202, etc.

On the other hand, apparatuses such as a mixer-settler type extractor aring and plate type extractor and or a column type extractor, which aregenerally also used in extraction processes with water, can not be usedfor the present process because of large amounts of product losses byrequiring a relatively long retention time of period, for example, fromseveral minutes to approximately 50 minutes or so.

A reasonable separation of two liquids having the small specific gravitydifferences is not attainable by short retention time of period in suchapparatuses.

Furthermore, small amounts of an alkali can be optionally used togetherwith water supplied in the form of counter-current for the purpose offurther effectively or completely removing the organic acid and organicperacid in the crude reaction solution.

For example, in the case of using a solvent such as ethyl acetatesmaller than water in the specific gravity, the aqueous alkali solutionis inevitably mixed at the zones where the concentrations of the organicacid and organic peracid become lower, more specifically at the slits orthe holes in the ring members or the perforated cylinders situated nearthe shaft.

It is noted that the concentrations difference of the organic acid andorganic peracid between in the crude reaction solution and in aqueoussolution act as a driving force for the transference of them into theaqueous solution.

Accordingly, there is preferably selected the use amounts of the alkalicorresponding to approximately 1% of the organic acid and organicperacid in the reaction solution, because of only supplementarilysupplying into the zones mentioned above.

Furthermore, it is noted that in the case of having relatively lowtheoretical plate numbers, the reaction solution can also be passedthrough repeatedly the centrifugal extractor to be used in the presentinvention supplying water by counter-current.

However, if there is not required a recovery of the organic acid andorganic peracid and a waste water treatment, the use amounts of thealkali are not limited.

The aqueous solution layer separated in the centrifugal extractor inwhich the organic acid and organic peracid extracted with water aredissolved, can not be generally discharged as a waste water without anytreatments from the viewpoint of prevention of environmental pollution.

However, for example, a treatment of the solution by a neutralizationwith an alkali can not be applied because of a substantially sameprocess as the neutralization before an extraction with water.

Accordingly, in the case that the boiling points of the organic acid andorganic peracid are lower than the boiling points of water, they can begenerally removed from the solution and they can be recovered withdistillation.

On the other hand, in the case that the boiling points of the organicacid and organic peracid are higher than the boiling points of water,the organic acid and organic peracid are removed and recovered by a backextraction method from the solution using a reagent for extracting, morespecifically an organic solvent.

Even in the case that the boiling points are higher than the boilingpoints of water, although distillation can be applied, it can not beapplied on an industrial basis because of considerably large energycosts due to evaporation of water.

The preferred solvents include benzene, toluene, xylene, ethylbenzene,isopropylbenzene, diethylbenzene, p-symene, etc. which are aromatichydrocarbons, cyclohexane, n-hexane, heptane, octane, nonane, decane,decalin, etc. which are aliphatic or alicyclic hydrocarbons, ethylacetate, n-amyl acetate, cyclohexyl acetate, iso-amyl propionate, methylester of benzoic acid which are ester compounds, chloroform, carbontetrachloride, chlorobenzene, etc. which are halogenated compounds,1,2-dimethoxyethane, diethyl ether, etc. which are ether compounds.

There can be preferably used the solvents much lower in boiling pointsthan the organic acid and organic peracid because of inevitably carryingout distillation after the back extraction.

Furthermore, there can be preferably used the solvents having a lowsolubility into water because of inevitably carrying out the waste watertreatments.

The water extraction process according to the first aspect of thepresent invention is preferably carried out at relatively lowertemperature conditions from the view point of the lower reactivity ofthe epoxy group in 3,4-epoxycyclohexyl methyl(meth)acrylate with theorganic acid.

However, too low temperature conditions occasionally make the propertyfor separating into the two solution layers lower because of an increaseof the viscosity and a decrease of the gravity differences.

Accordingly, the preferred temperature range is from 10° to 30° C., morepreferably from 15° to 25° C.

It is noted that the organic acid and also organic peracid should beremoved to the extent of less than 0.1%, preferably less than 0.05%,respectively, in the reaction solution after extraction in order tosufficiently remove the organic acid and organic peracid in a nextprocess which is an alkali neutralization process and from the viewpoint of reducing the load of a waste water treatment.

Although there is not limited the supplying ratio of water which is areagent for extracting the organic acid and organic peracid to the crudereaction solution in the extraction process with water, it is preferablyfrom 1/2 to 3/1 by weight in order to attain the above-mentionedconcentrations of the organic acid and peracid.

According to a second aspect of the present invention, there is providedan improved process for the preparation of a purified3,4-epoxycyclohexyl methyl(meth)acrylate by the epoxidation reaction ofcyclohexenyl methyl(meth)acrylate with an organic peracid, characterizedin that an organic acid and an organic peracid are removed from a crudereaction solution after the epoxidation reaction by extraction withwater and successively neutralized with an aqueous alkali solution.

In the second aspect of the present invention, a solution to be suppliedmust be the solution after extracting the organic acid and organicperacid with water, which is more specifically, the solution having theorganic acid and organic peracid of less than 0.1%, more preferably lessthan 0.05%.

And, the organic acid and organic peracid must be removed to the extentof less than 0.01% in the alkali neutralization in order to obtain apurified 3,4-epoxycyclohexyl methyl(meth)acrylate.

Although depending upon the concentrations of the residual organic acidand organic peracid after extraction with water, the concentration ofthe aqueous alkali is generally from 0.1% to 10%, more preferably from 1to 2%.

If it is more than 10%, for example, ethyl acetate which is a preferredsolvent in the epoxidation reaction occasionally exhibits the tendencyof a decomposition.

On the other hand, if it is less than 0.1%, the organic acid and organicperacid cannot sufficiently removed.

The preferred temperatures range is from 0° to 50° C., preferably from10° to 30° C. In the case of less than 0° C., it is difficult toseparate into two solution layers. On the other hand, in the case ofmore than 50° C., organic components tend to be dissolved into theaqueous alkali solution, resulting in increasing the load of a wastewater treatment.

The neutralization with the aqueous alkali can be carried out by acontinuous process or a batchwise process.

In the case of the continuous process, a mixer-settler type apparatuscan be preferably used.

It is noted that the above-mentioned centrifugal counter-currentextractor is not preferably used in the alkali neutralization processbecause of the short retention time of period, resulting in insufficientremoval of the organic acid and peracid.

In the case of the batchwise process, an extracting column typeapparatus can be preferably used.

In the alkali neutralization process, the residual (unreacted andremained in the extraction process with water) organic peracid must besufficiently removed together with the organic acid, for example, to theextent of not more than 0.01% by weight based on the reaction solution,for the purpose of a stabilized operation of evaporation in order toremove low-boiling ingredients.

According to a third aspect of the present invention, there is providedan improved process for the preparation of a purified3,4-epoxycyclohexylmethyl(meth)acrylate by the epoxidation reaction ofcyclohexenylmethyl(meth)acrylate with an organic peracid, characterizedin that a 3,4-epoxycyclohexyl methyl(meth)acrylate solution includinglow-boiling ingredients is refined by the step:

(a) evaporating components having low boiling points at temperatures notmore than 100° C. and at reduced pressures to obtain a crude epoxidizedsolution including low-boiling ingredients of from 3 to 50% by weightand successively

(b) evaporating the low-boiling ingredients at temperatures not morethan 100° C. and at less than 1/2 of the reduced pressures inabove-mentioned

(a) to obtain 3,4-epoxycyclohexenyl methyl(meth)acrylate including thelow-boiling ingredients of not more than 1% by weight.

The solution to be supplied into a first evaporator preferably has acomposition composed of 3,4-epoxycyclohexyl methyl(meth)acrylate whichis a primary desired product, small amounts of unreacted cyclohexenylmethyl(meth)acrylate which is a starting material, the small amounts ofthe organic peracid and the organic acid unremoved in the extractingprocess with water and/or in the neutralization process with the aqueousalkali solution, a solvent which is a primary low-boiling ingredients tobe evaporated, and further small amounts of by-products.

More specifically, the contents of the residual organic peracid andorganic acid in the solution must be preferably reduced to the extent ofless than 100 ppm, respectively.

If the contents are more than 100 ppm, the epoxy group in3,4-epoxycyclohexyl methyl(meth)acrylate reacts with the organic acidunder the influence of heating in evaporation, resulting inpolymerization of 3,4-epoxycyclohexyl methyl(meth)acrylate and incausing suspensions in a heptane test described hereinabove,specifically, a heptane test value of approximately 0.1% or more.

Although depending upon the kinds of solvents or organic peracids to beused in the epoxidation reaction, the preferred temperatures inevaporation are less than 100° C., more specifically from 40° to 60° C.,from the view point of preventing polymerization of 3,4-epoxycyclohexylmethyl(meth)acrylate.

If the temperatures are more than 100° C., there readily tends to causethe polymerization of 3,4-epoxycyclohexyl methyl(meth)acrylate andcyclohexenyl methyl(meth)acrylate, even though at small amounts of theorganic peracid and organic acid.

If the temperatures are less than 40° C., it is too low in theevaporation velocity.

The evaporations are preferably carried out with a thin-film evaporator.

The reduced pressures range in the first step evaporation is from 100 to200 Torr depending upon the kinds of solvents or organic peracids to beused in the epoxidation reaction, preferably from 100 to 150 Torr.

And, the reduced pressures range in the second step evaporation isessentially less than 1/2 of the first step reduced pressures,preferably from 1/3 to 1/4.

The low-boiling ingredients include solvents, water and minor amounts ofthe organic acid and organic peracid.

The evaporation process which is the third aspect of the presentinvention is characterized by being separated into the two stages havingdifferent evaporation conditions, and also particularly characterized bycontrolling the contents of the low-boiling ingredients remained in thefirst stage evaporation.

The third aspect is based on the mechanism that although initialevaporation of the low-boiling ingredients is relatively easy eventhough under lowerly reduced pressure conditions, final evaporation isrelatively difficult without highly reduced pressure conditions.

That is, the contents of the low-boiling ingredients are essentiallymaintained in the range of from 3 to 50% by weight based on the totalweight of the crude reaction solution, preferably from 5 to 20% byweight, more preferably 10% or so.

If the contents are less than 3% by weight, there is required the highlyreduced pressure in the first stage evaporation and the evaporatedsolvents can not be economically recovered without many losses in thecase of catching by a condenser.

On the other hand, if the contents are more than 50% by weight, solventscan not be economically recovered without many losses in the case ofcatching by a condenser because of the highly reduced pressures in thesecond stage.

The contents of the low-boiling ingredients in the product under thesecond stage evaporation are essentially not more than 1% by weight.

If the contents are more than 1%, the product primarily including3,4-epoxycyclohexyl methyl(meth)acrylate is not commercially available.

According to a fourth aspect of the present invention, there is provideda process for the preparation of a purified 3,4-epoxycyclohexenylmethyl(meth)acrylate from a crude reaction solution obtained by theepoxidation reaction of cyclohexenyl methyl(meth)acrylate with anorganic peracid, characterized by the step:

(a) extracting said organic peracid and an organic acid in the crudereaction solution derived from said organic peracid with water using acentrifugal extractor in which retention time is adjusted within lessthan 5 minutes in extracting with water to remove the organic peracidand an organic acid derived from the organic peracid,

(b) said organic solution layer being neutralized with an aqueous alkalisolution to form an organic solution layer and an aqueous solutionlayer, said organic solution layer being separated from said aqueoussolution layer,

and successively

(c) said organic solution layer being evaporated at temperatures notmore than 100° C. and at reduced pressures to obtain a3,4-epoxycyclohexenyl methyl(meth)acrylate solution includinglow-boiling ingredients of from 3 to 50% by weight,

and further

(d) said 3,4-epoxycyclohexenyl methyl(meth)acrylate solution beingevaporated at temperatures not more than 100° C. and at less than 1/2 ofthe reduced pressures in the above-mentioned (c) to obtain a purified3,4-epoxycyclohexenyl methyl(meth)acrylate including the low-boilingingredients of not more than 1% by weight.

The fourth aspect is composed of a series of the combination of theabove-mentioned first aspect, second aspect and third aspect.

According to a fifth aspect of the present invention, there is provideda 3,4-epoxycyclohexyl methyl(meth)acrylate composition including from0.01 to 0.1 parts by weight of an organic phosphorous compoundrepresented by general formulae (I) and/or (II) described hereinafter;##STR3## [in the formulae (I) and (II), R¹ to R⁸ are hydrogen, ahalogen, and or a monovalent aliphatic or aromatic substituent grouphaving carbon numbers of from 1 to 10, which may be same or different,respectively].

The organic phosphorous compounds are used for the purpose of preventingcoloring of 3,4-epoxycyclohexyl methyl(meth)acrylate, in the presentinvention.

As described previously, it is known that 3,4-epoxycyclohexylmethyl(meth)acrylate is exceedingly readily colored in the preparationprocesses, while being stored and/or shipped because of oxidation by airor other causes. For example, it appears as a mechanism of coloring that3,4-epoxycyclohexyl methyl(meth)acrylate itself polymerizes orby-reacts, even though in very minor amounts, because of its highreactivity.

The preferred color hue value in a commercially available3,4-epoxycyclohexyl methyl(meth)acrylate is usually less than 200 inAPHA value, if taking it into consideration of the various uses,desirably less than 100.

It may be generally considered that purification of 3,4-epoxycyclohexylmethyl(meth)acrylate by distillation is suitable for a method forpreventing coloring.

However, it is not preferable due to history of heating even thoughunder reduced pressures.

Accordingly, it appears that a chemical treatment or an absorptiontreatment is more preferable instead of distillation.

In the chemical treatment, for example, there have been added molecularstate oxygen, an oxidant such as hydrogen peroxide, a reducing agentsuch as sodium borohydride, sodium hydrogenatedbis(2-methoxyethoxy)aluminum, a polymerization inhibitor such ashydroquinone, an antioxidant such as BHT(2,6-ditertbutyl-4-methyl-phenol), BHA (butyl hydroxy anisole), ablocking agent for metal such as EDTA, trioctyl phthalate, etc. in thepreparation processes.

In the absorption treatment, for example, it is known that there havebeen used an activated carbon which is a most conventional absorbent, anactivated clay, zeolite, a highly porous polymer, etc.

However, there are only very minor effects for preventing coloring orfor discoloring according to such conventional chemical treatment orabsorption treatment.

Furthermore, Japanese Patent Application No. 191267/1990 discloses theuse of a hydrotalcite compound for removing coloring components in3,4-epoxycyclohexyl methyl(meth)acrylate.

However, there causes coloring again after a long time of period in theuse of the compound.

The essential organic phosphorous compound include3,4,5,6-dibenzo-1,2-oxaphosphane-2-oxide,9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (for example, HCAwhich is a trade name, manufactured by Sanko Chemical, Ltd.),6,8-dichloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide,6,8-di(tert-butyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide,etc., and further a hydrated compound thereof.

The organic phosphorous compounds are represented by formula (I);##STR4## and the hydrated compound are represented by formula (II);##STR5## [in the formulae (I) and (II), R¹ to R⁸ are hydrogen, ahalogen, and or a monovalent aliphatic or aromatic substituent grouphaving carbon numbers of from 1 to 10, which may be same or different,respectively].

The organic phosphorous compounds can be added either in the form ofpowder or a solution with a solvent.

Although the organic phosphorous compounds may also be added even in theeach step of the present preparation process, it is preferably mixed ina final product.

The use amounts of the compound represented by formulae (I) and (II) areessentially from 0.001 to 1 part, preferably from 0.01 to 0.2 part byweight.

If the use amounts are less than 0.001 parts by weight, the effect as apolymerization inhibitor is small.

On the other hand, if the use amounts are more than 1 part by weight,there causes an adverse affection instead of the effect as apolymerization inhibitor.

According to a sixth aspect of the present invention, there is provided3,4-epoxycyclohexyl methyl(meth)acrylate having a heptane test value ofless than 0.1% by weight.

The 3,4-epoxycyclohexyl methyl(meth)acrylate having a heptane test valueof less than 0.1% by weight can be prepared by the combined processes ofthe above-mentioned first aspect, second aspect and third aspect, and orfourth aspect alone.

The heptane test value relating to a conventional 3,4-epoxycyclohexylmethyl(meth)acrylate has been more than 0.1% by weight, morespecifically approximately 0.14% by weight or so.

The heptane test value corresponds to the amounts of polymers having alow molecular weight composed of 3,4-epoxycyclohexylmethyl(meth)acrylate itself.

The contents of the polymers having a low molecular weight can be shownby weight % with a measuring method using n-heptane or n-hexane, inwhich 10 g of a product is dissolved in 100 cc of n-heptane or n-hexaneand resulting suspensions are filtered and weighed.

3,4-epoxycyclohexyl methyl(meth)acrylate prepared by the combinedprocesses of the above-mentioned first aspect, second aspect and thirdaspect, and or fourth aspect alone exhibits usually the heptane testvalue of 0.02% by weight or so.

In the following, Synthesis Examples, Examples and Comparative Examplesare described in order to more specifically illustrate the presentinvention.

[Synthesis Example 1--Preparation of a crude reaction solution including3,4-epoxycyclohexyl methyl methacrylate]

A SUS 316-made reaction vessel having a capacity of 15 liter equippedwith a stirrer and a jacket for cooling was charged with 3913 parts of3-cyclohexenyl methyl(meth)acrylate (hereinafter, referred to as CHMA),7826 parts of ethyl acetate, 5.85 parts of hydroquinone monomethyletherwhich is a polymerization inhibitor and 2.35 parts of sodiumtripolyphosphate which is a stabilizer for a peracid, followed byraising the internal temperature to 45° C.

Successively, 6329 parts of ethyl acetate solution including 30% ofperacetic acid was added dropwise over 4 hours, followed by aging for 2hours. The internal temperature was maintained at 50° C. while addingdropwise and aging, to obtain 18076 parts of a crude reaction solutionincluding 3,4-epoxycyclohexyl methyl methacrylate (hereinafter, referredto as METHB).

[Example 1--a water extraction test with a centrifugal extractor]

The crude reaction solution obtained in Synthesis Example 1 wasintroduced from an inlet for a light solution phase at 2108 g/minute andwater was introduced from an inlet for a heavy solution phase at 3590g/minute into a counter-current type centrifugal extractor (havingpriming volume of 2400 ml) equipped with a rotor having an outerdiameter of 46 cm and an inner diameter of 25 mm which rotates at 4000r.p.m.

And, a light solution layer was obtained at 1664 g/minute from an outletfor the light solution layer and a heavy solution layer was obtained at4034 g/minute from an outlet for the heavy solution layer.

Retention time of period in the centrifugal extractor was approximately25 seconds.

The light solution layer was introduced again from the inlet for thelight solution layer at 2108 g/minute and water was introduced from theinlet for the heavy solution layer at 3590 g/minute.

And, a light solution layer was obtained at 1877 g/minute from theoutlet for the light solution layer and a heavy solution layer wasobtained at 3821 g/minute from the outlet for the heavy solution layer.

Retention time of period in the centrifugal extractor was approximately25 seconds.

Accordingly, the total retention time of period was approximately 50seconds.

The concentrations of acetic acid and peracetic acid in the crudereaction solution before extracting with water were 10.66% and 1.15%,respectively.

The concentrations of acetic acid and peracetic acid in the lightsolution layer after extracting in twice with water were 400 ppm and 150ppm, respectively.

99% of METHB dissolved in the crude reaction solution was recovered inthe light solution layer after extracting in twice with water.

[Comparative Example 1--a water extraction test supposing a column typeextractor]

A flask having a capacity of 2 liter equipped with a stirrer was chargedwith 1000 parts of a crude reaction solution obtained by the sameprocedures as described in Synthesis Example 1 and 1000 parts of water,followed by agitating for 60 minutes at 20° C. and settling for 30minutes.

As the result, approximately 5% of METHB dissolved in the crude reactionsolution disappeared under the influence of the reaction of METHB withan aqueous acetic acid solution.

[Synthesis Example 2--Preparation of a crude reaction solution including3,4-epoxycyclohexyl methyl acrylate]

A SUS 816-made reaction vessel having a capacity of 20 liter equippedwith a stirrer and a jacket for cooling was charged with 3000 parts of3-cyclohexenyl methyl acrylate (hereinafter, referred to as CHAA), 11100parts of ethyl acetate, 0.9 part of hydroquinone monomethylether whichis a polymerization inhibitor and 9.0 parts of sodium tripolyphosphate,followed by introducing a mixed gas composed of oxygen and nitrogen(oxygen/nitrogen=10/90 by volume) at 32 normal liter/hour from a tubeand raising the internal temperature to 40° C.

Successively, 5623 parts of ethyl acetate solution including 30% ofperacetic acid was added dropwise over 4 hours with a pump maintainingthe reaction temperature at 40° C., followed by aging for 5 hours afterthe addition of peracetic acid to complete the epoxidation reaction andto obtain 19723 parts of a crude reaction solution including3,4-epoxycyclohexyl methyl acrylate (hereinafter, referred to as AETHB).

[Example 2--a water extraction test with a centrifugal extractor]

The crude reaction solution obtained in Synthesis Example 2 wasintroduced from an inlet for a light solution phase at 2108 g/minute andwater was introduced from an inlet for a heavy solution phase at 3621g/minute into a counter-current type centrifugal extractor (havingpriming volume of 2400 ml) equipped with a rotor having an outerdiameter of 46 cm and an inner diameter of 25 mm which rotates at 4000r.p.m.

And, a light solution layer was obtained at 1713 g/minute from an outletfor the light solution phase and a heavy solution layer was obtained at4016 g/minute from an outlet for the heavy solution phase.

Retention time of period in the centrifugal extractor was approximately25 seconds.

The light solution layer was introduced again from the inlet for thelight solution phase at 2108 g/minute and water was introduced from theinlet for the heavy solution phase at 3590 g/minute.

And, a light solution layer was obtained at 1865 g/minute from theoutlet for the light solution phase and a heavy solution layer wasobtained at 3833 g/minute from the outlet for the heavy solution phase.

Retention time of period in the centrifugal extractor was approximately25 seconds.

Accordingly, the total retention time of period was approximately 50seconds.

The concentrations of acetic acid and peracetic acid in the crudereaction solution before extracting with water were 8.96% and 1.51%,respectively.

The concentrations of acetic acid and peracetic acid in the lightsolution layer after extracting in twice with water were 400 ppm and 150ppm, respectively.

99% of AETHB dissolved in the crude reaction solution was recovered inthe light solution layer after extracting in twice with water.

[Example 3--an alkali neutralization test]

A SUS 316-made vessel for mixing equipped with a stirrer and a jacketfor cooling having a capacity of 15 liter was charged with 3000 parts ofthe light solution layer obtained in Example 2, successively, 3000 partsof an aqueous solution including 1% of NaOH was charged into the vessel,followed by agitating for 1 hour maintaining at the temperature of 10°C.

After settling for 30 minutes, 2790 parts of an upper solution layer wasseparated from a lower solution layer.

The concentrations of acetic acid and peracetic acid in the uppersolution layer were less than 100 ppm, respectively.

[Example 4--an alkali neutralization test]

The same procedures as described in Example 3 were repeated, except thatthere was charged 3000 parts of an aqueous solution including 0.5% ofNaOH.

The concentrations of acetic acid and peracetic acid in the uppersolution layer were less than 100 ppm, respectively.

[Example 5--an alkali neutralization test]

The same procedures as described in Example 5 were repeated, except thatthere was charged 3000 parts of an aqueous solution including 0.1% ofNaOH.

The concentrations of acetic acid and peracetic acid in the uppersolution layer were less than 100 ppm, respectively.

[Example 6--an alkali neutralization test]

The same procedures as described in Example 3 were repeated, except thatthere was charged 300 parts of an aqueous solution including 1% of NaOH.The concentrations of acetic acid and peracetic acid in the uppersolution layer were less than 100 ppm, respectively.

[Comparative Example 2--a water extraction test supposing a column typeextractor]

A SUS316-made mixing vessel having a capacity of 15 liter equipped witha stirrer was charged with 3000 parts of a crude reaction solutionobtained by the same procedures as described in Synthesis Example 2 and3000 parts of a distilled water, followed by agitating for 60 minutes at10° C. and settling for 60 minutes, resulting in two solution layers.

2790 parts of the light solution layer was separated from the heavysolution layer.

As the result, approximately 5% of AETHB dissolved in the crude reactionsolution disappeared under the influence of the reaction of AETHB withan aqueous acetic acid.

[Comparative Example 3--an evaporation test after a water extractiontest supposing a column type extractor and without neutralization withan aqueous alkali solution]

0.21 part of hydroquinone monomethylether was added in 2790 parts of theupper solution layer obtained in Comparative Example 2, the solution wassupplied into a SUS-made Smith falling film type evaporator maintainedat the temperature of 60° C. and the reduced pressure of 150 mm Hgsupplying a mixed gas composed of oxygen and nitrogen at 32 liter/hourfrom the bottom of the evaporator, to which a line for discharging aliquid is connected, to obtain a solution including 5% of low boilingcomponents.

Successively, the solution discharged from the bottom was supplied againinto the SUS-made Smith falling film type evaporator at the temperatureof 60° C. and the reduced pressure of 40 mm Hg supplying a mixed gascomposed of oxygen and nitrogen at 32 liter/hour from the bottom of theevaporator to which a line for discharging a liquid is connected, toobtain 538 parts of a product including not more than 1% of low boilingingredients.

The concentration of AETHB in the product was 86.5% by a gaschromatography analysis.

[Example 7--an evaporation test]

0.21 part of hydroquinone monomethylether was added in 2790 parts of theupper solution layer obtained in Example 3, the solution was suppliedinto a SUS-made Smith falling film type evaporator maintained at thetemperature of 60° C. and the reduced pressure of 150 mm Hg supplying amixed gas composed of oxygen and nitrogen at 32 liter/hour from thebottom of the evaporator, to which a line for discharging a liquid isconnected, to obtain a solution including 5% of low-boiling ingredients.

Successively, the solution discharged from the bottom was supplied againinto the SUS-made Smith falling film type evaporator at the temperatureof 60° C. and the reduced pressure of 40 mm Hg supplying a mixed gascomposed of oxygen and nitrogen at 32 liter/hour from the bottom of theevaporator to which a line for discharging a liquid is connected, toobtain 538 parts of a product including not more than 1% of low-boilingingredients.

The concentration of AETHB in the product was 96.4% by a gaschromatography analysis.

The heptane test value of the product was 0.02%.

[Example 8--an evaporation test]

The same procedures as described in Example 7 were repeated, except thatthe upper solution layer obtained in Example 4 was used to obtain 538parts of a product. The concentration of AETHB in the product was 95.7%by a gas chromatography analysis.

The heptane test value of the product was 0.02%.

[Comparative Example 4--an evaporation test without neutralization withalkali after extracting with water]

0.21 part of hydroquinone monomethylether was added in 2300 parts of thesame upper solution layer as obtained in Example 1, the solution wassupplied into a SUS-made Smith falling film type evaporator maintainedat the temperature of 60° C. and the reduced pressure of 150 mm Hgsupplying a mixed gas composed of oxygen and nitrogen at 32 liter/hourfrom the bottom of the evaporator, to which a line for discharging aliquid is connected, to obtain a solution including 5% of low-boilingingredients.

Successively, the solution discharged from the bottom was supplied againinto the SUS-made Smith falling film type evaporator at the temperatureof 60° C. and the reduced pressure of 40 mm Hg supplying a mixed gascomposed of oxygen and nitrogen at 32 liter/hour from the bottom of theevaporator to which a line for discharging a liquid is connected, toobtain a product including not more than 1% of low-boiling ingredients.

The concentration of METHB in the product was 89.5% by a gaschromatography analysis.

[Example 9--a coloring test after mixing an organic phosphorouscompound]

0.1 part of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was mixedwith 100 parts of the product which has a color hue of 40 in APHA valueobtained in Example 7.

The mixture was stored for three months at 30° C. As the result, theAPHA value changed to 50.

[Comparative Example 4--a coloring test without mixing an organicphosphorous compound]

The product which has a color hue of 40 in APHA value obtained inExample 7 without mixing any additives was stored for three months at30° C. As the result, the APHA value changed to 400.

[Comparative Example 5--a coloring test after mixing large amounts of anorganic phosphorous compound]

1 part of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was mixedwith 100 parts of the product which has AETHB contents of 96.4 obtainedin Example 7. The mixture was stored for three months at 30° C. As theresult, the AETHB contents changed to 91.2%.

[Comparative Example 6 a coloring test after mixing small amounts of anorganic phosphorous compound]

0.001 part of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide wasmixed with 100 parts of the product which has a color hue of 40 in APHAvalue obtained in Example 7. The mixture was stored for three months at30° C. As the result, the APHA value changed to 130.

[Comparative Example 7--a coloring test after mixing of a conventionalcoloring inhibitor]

0.1 part of BHT which is an antioxidant was mixed with 100 parts of theproduct which has a color hue of 40 in APHA value obtained in Example 7.The mixture was stored for three months at 80° C. As the result, theAPHA value changed to 150.

[Comparative Example 8--a coloring test after mixing of a conventionalcoloring inhibitor]

0.1 part of BHA which is an antioxidant was mixed with 100 parts of theproduct which has a color hue of 40 in APHA value obtained in Example 7.The mixture was stored for three months at 30° C. As the result, theAPHA value changed to 180.

[Comparative Example 9--a coloring test after mixing of a conventionalcoloring inhibitor]

0.1 part of Irganox (manufactured by Ciba-Geigy Corp.) which is anantioxidant was mixed with 100 parts of the product which has a colorhue of 40 in APHA value obtained in Example 7.

The mixture was stored for three months at 30° C. As the result, theAPHA value changed to 160.

[Comparative Example 10--a coloring test after mixing of a conventionalcoloring inhibitor]

0.1 part of Sanol (manufactured by Ciba-Geigy Corp.) which is anantioxidant was mixed with 100 parts of the product which has a colorhue of 40 in APHA value obtained in Example 7.

The mixture was stored for three months at 30° C. As the result, theAPHA value changed to 350.

[Comparative Example 11--an evaporation test after alkali neutralizationtreatments thrice without extraction with water]

3000 parts of a crude reaction solution obtained by the same proceduresas described in Synthesis Example 2 was mixed with 2500 parts of anaqueous solution including 10% of NaOH, followed by stirring for 30minutes and settling for 30 minutes, and then followed by separating thereaction solution.

The separated solution was mixed again with 2500 parts of an aqueoussolution including 10% of NaOH, followed by stirring for 30 minutes andsettling for 30 minutes, and then followed by separating the reactionsolution.

The contents of peracetic acid in the separated solution were 0.02%, andacetic acid was completely removed.

The separated solution was further mixed with 2500 parts of an aqueoussolution including 1% of NaOH, followed by stirring for 30 minutes andsettling for 30 minutes, and then followed by separating the reactionsolution. The contents of peracetic acid in the separated solution wereless than 100 ppm.

The same procedures as described in Example 7 were repeated, except thatthe solution obtained in the alkali neutralization treatments was usedto obtain a product.

The concentration of AETHB in the product was 94.5% by a gaschromatography analysis. And, the contents of ethyl acetate, CHAA andother components were 1.8%, 1.0% and 2.7%, respectively.

The heptane test value of the product was 0.25%, despite of evaporationin peracetic acid contents of less than 100 ppm and complete removal ofacetic acid, because of a long contacting time under the coexistence ofperacetic acid, acetic acid and water.

[Examples 10 to 12--water extraction tests with a centrifugal extractor]

Same procedures as described in Example 1 were repeated, except that thereaction crude solution containing 3,4-epoxycyclohexylmethylmethacrlate(METHB) obtained in Synthesis Example 1 was chargedinto the centrifugal extractor while adjusting charging speeds[corresponding to the respective retention time of period (R.T)] asshown in Table 1.

                  TABLE 1                                                         ______________________________________                                               A1    B1      A2      B2    R.T.  R.R.                                 ______________________________________                                        Example 10                                                                             586     997     583   994    91   99                                 Example 11                                                                             351     615     348   611   299   97                                 Example 12                                                                             176     305     178   310   594   96                                 ______________________________________                                         A1: Charging speed (g/minute) of reaction crude solution in first             extraction                                                                    B1: Charging speed (g/minute) of water in first extraction                    A2: Charging speed (g/minute) of reaction crude solution in second            extraction                                                                    B2: Charging speed (g/minute) of water in second extraction                   R.T.: Retention time of period (second)                                       R.R.: Recovery ratio (%) of METHB                                             99%, 97% and 96% of METHB dissolved in the crude reaction solution were       recovered in the light solution layer after extracting in twice with          water, respectively.                                                     

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A process for the preparation of purified3,4-epoxycyclohexyl methyl(meth)acrylate prepared by an epoxidationreaction of cyclohexenyl methyl(meth)acrylate with an organic peracid,comprising removing organic acid derived from the organic peracid usedin the epoxidation reaction and the organic peracid from an epoxidationcrude reaction product by extracting the crude reaction product withwater in a centrifugal extractor wherein retention time of period ofextraction in the centrifugal extractor is up to about 5 minutes.
 2. Aprocess for the preparation of purified 3,4-epoxycyclohexylmethyl(meth)acrylate prepared by an epoxidation reaction of cyclohexenylmethyl(meth)acrylate with an organic peracid, comprising refining theorganic peracid and an organic acid derived from the organic peracidused in the epoxidation reaction from a crude reaction solution afterthe epoxidation reaction by extracting the crude reaction solution withwater and successively neutralizing with an aqueous alkali solution, andfurther separating said crude reaction solution by static gravity.
 3. Aprocess for the preparation of purified 3,4-epoxycyclohexylmethyl(meth)acrylate prepared by an epoxidation reaction of cyclohexenylmethyl(meth)acrylate with an organic peracid, comprising removing a3,4-epoxycyclohexyl methyl(meth)acrylate solution including low-boilingingredients and substantially no water by:(a) evaporating thelow-boiling ingredients at temperatures not more than 100° C. and atreduced pressures to obtain a crude epoxidized solution including thelow-boiling ingredients of from 3 to 50% by weight, and successively (b)evaporating the low-boiling ingredients at temperatures not more than100° C. and at less than 1/2 of the reduced pressures in theabove-mentioned (a) to obtain 3,4-epoxycyclohexenyl methyl(meth)acrylateincluding the low-boiling ingredients of not more than 1% by weight. 4.A process as set forth in any one of claims 1, 2 or 3, wherein saidorganic peracid is peracetic acid and said organic acid derived from theorganic peracid is acetic acid.
 5. A process as set forth in claim 3,wherein said 3,4-epoxycyclohexenyl methyl(meth)acrylate solutionincludes less than 100 ppm of the organic peracid and organic acid,respectively.
 6. A process for the preparation of purified3,4-epoxycyclohexenyl methyl(meth)acrylate from a crude reactionsolution obtained by the epoxidation reaction of cyclohexenylmethyl(meth)acrylate with an organic peracid, comprising:(a) extractingsaid organic peracid and an organic acid derived from the organicperacid in the crude reaction solution with water using a centrifugalextractor in which retention time of period of extraction is up to about5 minutes in extracting water to remove the organic peracid and theorganic acid derived from the organic peracid and forming an organicsolution layer, (b) neutralizing said organic solution layer after thewater extraction with an aqueous alkali solution to form a neutralizedorganic solution layer and an aqueous solution layer, separating saidneutralized organic solution layer from said aqueous solution layer, (c)evaporating said organic neutralized solution layer at temperatures notmore than 100° C. and at reduced pressures to obtain a purified3,4-epoxycyclohexenyl methyl(meth)acrylate solution includinglow-boiling ingredients of from 3 to 50% by weight,and further (d)evaporating said 3,4-epoxycyclohexenyl methyl(meth)acrylate solution attemperatures not more than 100° C. and at less than 1/2 of the reducedpressures in the above-mentioned (c) to obtain a purified3,4-epoxycyclohexenyl methyl(meth)acrylate including the low-boilingingredients of not more than 1% by weight.
 7. A process as set forth inclaim 6, wherein said organic peracid is peracetic acid and said organicacid derived from said organic peracid is acetic acid.